OT: whatever. It's obvious what they meant even though they took a terrible way of saying it.
Regarding at wills, well, they say they are. And it's mechanical flavor, not non-mechanical, and certainly has an effect in some situations -- the Primal Vampire, Primal Fury, Spirits of Stone, Staggering Smash, and Predatory Spirit feats all trigger off primal powers, as does the Cavern Explorer's weapon.
Regardless, it's simply not even worth trying to figure out what they're doing, as they state it on the can. The Berserker is a barbarian who is a Martial Defender until she decides to rage (by using a primal power or spending a minor action while bloodied) -- and then she's a Primal Striker. So by default, all powers she can/wants to use as a defender are martial, and all powers she can (and wants to) use as a striker are primal -- and the dual nature of her at wills is part of this.